1. Field of the Invention
The present invention relates to an optical device and a method for manufacturing the same.
2. Description of the Related Art
Since a light-emitting diode (LED) is highly efficient and has a long lifespan, the LED drastically reduces energy consumption and has attracted much attention as an environmentally friendly optical device.
Recently, advanced display devices and illuminators have been developed using light-emitting diodes (LEDs), and in addition, LEDs in portable phone keypads/flashes and automobile headlights/pilot lights have been manufactured.
In particular, since blue LEDs using a nitride semiconductor material may be applied in various fields, such as LED white illuminators or backlight units (BLUs) of liquid crystal display televisions (LCD TVs), vast amounts of research and investment in blue LEDs are being realized.
However, it is difficult to employ a light-emitting semiconductor as a large-area display device or as a light source for an illuminator. In particular, it is difficult to manufacture an LED on a large area, and the LED has low price competitiveness.
Since the LED uses a single crystalline substrate, fabrication costs are high and limitations with the sizes of products are problematic.
Accordingly, to enable the scaling-up of size and low-cost manufacturing of LEDs, it is highly desirable to develop a short-wavelength optical device using an amorphous substrate capable of a low-cost large-area manufacturing process.
However, it is difficult to manufacture a highly efficient LED using a nitride semiconductor material on an amorphous substrate. This is because when a nitride thin layer is formed on the amorphous substrate, a polycrystalline thin layer is formed.
Accordingly, an LED using a polycrystalline nitride thin layer is inferior in device characteristics and efficiency to an LED using a single crystalline nitride semiconductor material manufactured on a single crystalline sapphire substrate.
The present invention is directed to an optical device, which uses an amorphous substrate and forms a semiconductor unit having a high crystallinity to improve electrical and optical properties, and a method of manufacturing the same.